The present invention relates to a trimming apparatus and more specifically to an apparatus for trimming an opening from a blow-molded container such as a universal portable urinal or the like.
Portable urinals or urine bottles are commonly used by people unable to gain access to normal facilities, such as by bedridden patients in a hospital. Significant disadvantages surround commonly used portable urinals. Most portable urinals are designed to be used by only one sex or the other, requiring hospitals and care providers to maintain inventories of both male and female urinals.
Attempts have been made to produce a universal urinal which is usable by both males and female patients. For example, U.S. Pat. No. 4,665,571 ('571 patent) teaches a portable urinal with an oval mouth which is designed to accommodate a female anatomy. The oval mouth, when viewed from either side of the urinal, presents a concave outline, while, from either end a convex outline is presented. The overall shape is said to be a closed loop on the surface of an imaginary cylinder with an axis parallel to the width of the mouth. The mouth has an inwardly directed flange to avoid sharp edges which could contact a male user's genitalia, and thus, the urinal is said to usable by both male and female patients.
While the design of the universal portable urinal, as taught by the '571 patent, is generally satisfactory, the manufacture of such a container has proven to be problematical. Such portable urinals are usually blow-molded, which is a process in which a plastic material is continuously extruded from an orifice in the shape of a hollow tube. A pair of mold halves enclose a segment of the tube and air is blown into the tube to expand it to the mold configuration. The resultant container is completely enclosed and, to yield a functional portable urinal, an alternately concave and convex oval plastic portion covering the urinal mouth must be cut away.
However, cutting an opening in a blow-molded container without leaving a sharp inner edge has been difficult with available prior art tools and techniques. This is especially true with respect to a urinal such as that disclosed in the '571 patent, where the mouth must be cut smooth enough so as not to present a hazard to a male user.
Trimming an alternately concave and convex oval, such as a universal urinal mouth, with a knife blade moved in a single plane results in knife chatter, thus creating sharp cerrations on the cut plastic and placing undue strain on the knife blade. Such a technique creates an unacceptably rough mouth opening. Sanding or otherwise smoothing the rough opening results in the production of tiny plastic burrs which become statically charged and attracted to the urinal container surface, thus making it very difficult to clean. Such labor intensive operations are not economically viable in any case.
It is clear then, that a need exists for a trimming apparatus which can trim an alternately concave and convex oval opening in a blow molded receptacle, such as a universal portable urinal, without leaving sharp edges. Such a trimming apparatus must be efficient, capable of yielding relatively large numbers of finished products within a reasonable time, must not create statically charged plastic burrs and, for reasons of economics, must not be labor intensive.